fix various iterator issues (fixes #181)
diff --git a/example/issues.ref b/example/issues.ref
index fce7b95..6d9a893 100644
--- a/example/issues.ref
+++ b/example/issues.ref
@@ -3,3 +3,4 @@
 Failed as expected: Tried to call pure virtual function "dispatch"
 Yay..
 [Placeholder[1], Placeholder[2], Placeholder[3], Placeholder[4]]
+[3, 5, 7, 9, 11, 13, 15]